igc/igb: Fix missing time sync events #51
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Fix "double" clearing of interrupts, which can cause external events or timestamps to be missed. The IGC_TSIRC Time Sync Interrupt Cause register can be cleared in two ways, by either reading it or by writing '1' into the specific cause bit. This is documented in section 8.16.1. The following flow was used: 1. read IGC_TSIRC into 'tsicr'; 2. handle the interrupts present in 'tsirc' and mark them in 'ack'; 3. write 'ack' into IGC_TSICR; As both (1) and (3) will clear the interrupt cause, if the same interrupt happens again between (1) and (3) it will be ignored, causing events to be missed. Remove the extra clear in (3). Fixes: 2c344ae ("igc: Add support for TX timestamping") Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de> Tested-by: Kurt Kanzenbach <kurt@linutronix.de> # Intel i225 Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Fix "double" clearing of interrupts, which can cause external events
or timestamps to be missed.
The E1000_TSIRC Time Sync Interrupt Cause register can be cleared in two
ways, by either reading it or by writing '1' into the specific cause
bit. This is documented in section 8.16.1.
The following flow was used:
1. read E1000_TSIRC into 'tsicr';
2. handle the interrupts present into 'tsirc' and mark them in 'ack';
3. write 'ack' into E1000_TSICR;
As both (1) and (3) will clear the interrupt cause, if the same
interrupt happens again between (1) and (3) it will be ignored,
causing events to be missed.
Remove the extra clear in (3).
Fixes: 00c6557 ("igb: enable internal PPS for the i210")
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
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This is a backport to kernel 6.1 of the fix proposed here:
https://lore.kernel.org/all/20240220235712.241552-1-vinicius.gomes@intel.com/
In short, the drivers (igc and igb) were double clearing the Time Sync Interrupt Cause register, which can cause events to be missed.